...
\{
  "card_index": 0,
  "type": "product",
  "action": {
    "product_retailer_id": "abc123xyz",
    "catalog_id": "123456789"
}
...

curl 'https://graph.facebook.com/<API_VERSION>/<WHATSAPP_BUSINESS_PHONE_NUMBER_ID>/messages' \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer <ACCESS_TOKEN>' \
  -d '{
    "messaging_product": "whatsapp",
    "recipient_type": "individual",
    "to": "<WHATSAPP_USER_PHONE_NUMBER>",
    "type": "interactive", // must be interactive
    "interactive": {
      "type": "carousel", // must be carousel
      "body": {
        "text": "<MESSAGE_BODY_TEXT>"
      },
      "action": {
        "cards": [\
          {\
            "card_index": 0,\
            "type": "product",\
            "action": {\
              "product_retailer_id": "abc123xyz",\
              "catalog_id": "123456789"\
            }\
          }\
          // additional product cards\
        ]
      }
    }
  }'

...
\{
  "card_index": <INDEX>,
  "type": "product",
  "action": {
    "product_retailer_id": "<PRODUCT_RETAILER_ID>",
    "catalog_id": "<CATALOG_ID>"
}
...

\{
  "messaging_product": "whatsapp",
  "recipient_type": "individual",
  "to": "1234567890",
  "type": "interactive",
  "interactive": {
    "type": "carousel",
    "body": {
      "text": "Check out our featured products!"
    },
    "action": {
      "cards": [\
        {\
          "card_index": 0,\
          "type": "product",\
          "action": {\
            "product_retailer_id": "abc123xyz",\
            "catalog_id": "123456789"\
          }\
        },\
        {\
          "card_index": 1,\
          "type": "product",\
          "action": {\
            "product_retailer_id": "def456uvw",\
            "catalog_id": "123456789"\
          }\
        }\
      ]
    }
  }
}

\{
  "messaging_product": "whatsapp",
  "contacts": [\
    {\
      "input": "+16505551234",\
      "wa_id": "16505551234"\
    }\
  ],
  "messages": [\
    {\
      "id": "wamid.HBgLMTY0NjcwNDM1OTUVAgARGBI1RjQyNUE3NEYxMzAzMzQ5MkEA"\
    }\
  ]
}